It is going to depend greatly on the barrel/ammo match up..........basically like any other gun. I have 4 different slug guns, 2 smooth bores/2 rifled. They all like different ammo, with that said.........I would try a basic Remington folster style rifled slug for smooth bores and the Brenneke Heavy field short magnum slugs(which can be shot from smooth bore or rifled barrels)
PM me if you would care to discuss the topic in more detail
FDXX75